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Prashanth
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 Posted: Wed Dec 03, 2003 2:32 pm Post subject: Static and Stagnation properties |
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What are Static properties? Does he presence of the word "Static" mean
tha it is the property of the fluid when it is measured at rest? If
So, then
What is the difference between Static Pressure and Stagnation
Pressure? (As textbooks say that stagnation property is the one when
the fluid is decellerated to zero velocity at zero datum.- Doesn>t
this mean Staticity or at rest) |
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Ed Ruf
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| Posted: Wed Dec 03, 2003 6:41 pm Post subject: Re: Static and Stagnation properties |
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On 3 Dec 2003 00:32:36 -0800, in sci.mech.fluids
prashanthramu@hotmail.com (Prashanth) wrote:
[quote]What are Static properties? Does he presence of the word "Static" mean
tha it is the property of the fluid when it is measured at rest? If
[/quote]
While some definitions of static pressure talk about a fluid at rest,
it is more appropriately thought of as the pressure which would be
measured by an instrument that moves along with the fluid.
[quote]What is the difference between Static Pressure and Stagnation
Pressure? (As textbooks say that stagnation property is the one when
the fluid is decellerated to zero velocity at zero datum.- Doesn>t
this mean Staticity or at rest)
[/quote]
Stagnation pressure is the pressure one would have after
isentropically (no losses) decelerating the fluid to a rest.
Think of Bernoulli>s eqn,
p + 0.5*rho*U^2 = const.
This p is the static pressure. The stagnation pressure is the whole
expression. A common way to measure this pressure is through the use
of wall pressure taps. |
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John
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| Posted: Fri Dec 05, 2003 8:31 am Post subject: Re: Static and Stagnation properties |
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Static pressure is the result of compressive forces only, whether at rest or
in motion.
Stagnation pressure is the result of compressive and motive forces
isentropically acting upon a fluid at rest.
--
John
If you Reply, be sure and remove the " (DELETE_THIS) " from the email
address.
"Prashanth" <prashanthramu@hotmail.com> wrote in message
news:e160c203.0312030032.73b7ecf7@posting.google.com...
[quote]What are Static properties? Does he presence of the word "Static" mean
tha it is the property of the fluid when it is measured at rest? If
So, then
What is the difference between Static Pressure and Stagnation
Pressure? (As textbooks say that stagnation property is the one when
the fluid is decellerated to zero velocity at zero datum.- Doesn>t
this mean Staticity or at rest)[/quote] |
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Frank Dodge
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| Posted: Mon Dec 08, 2003 7:28 am Post subject: Re: Static and Stagnation properties |
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Static pressure is, as you say, the pressure you would measure at a point in
a fluid that is not moving, and it is also the pressure you would measure in
a fluid that is everywhere moving with the same velocity so long as your
measurement doesnt change the velocity of the fluid. Stagnation pressure is
the pressure measured at a point where a fluid that is moving elsewhere is
brought to rest and therefore includes the effect of the force or pressure
that is required to bring the fluid to rest at that point. The stagnation
pressure is therefore larger than the static pressure. The difference is
also called the velocity pressure.
"Prashanth" <prashanthramu@hotmail.com> wrote in message
news:e160c203.0312030032.73b7ecf7@posting.google.com...
[quote]What are Static properties? Does he presence of the word "Static" mean
tha it is the property of the fluid when it is measured at rest? If
So, then
What is the difference between Static Pressure and Stagnation
Pressure? (As textbooks say that stagnation property is the one when
the fluid is decellerated to zero velocity at zero datum.- Doesn>t
this mean Staticity or at rest)[/quote] |
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